Two-piece piston

ABSTRACT

A counterbalancing device for use with an electrical disconnect switch comprises a cylinder which houses a piston, a piston rod and a biasing spring which bears against the piston. The cylinder is a length of standard metal pipe or tubing. The piston rod is a flat bar stock having one or more holes provided along its length. The piston comprises two identical separate cast metal semicircular pieces which have reentrant projections on one face thereof which engage a hole in the piston rod.

United States Patent Inventor Calvin E. Redlern 1,994,861 3/1935 Meyer 92/255 Portland 0113 Primary Examiner-Martin P. Schwadron App]. No. 865,733

AS81810!!! Exammer Ronald Lazarus, Med I969 Attorneys-Thomas F. Kirby, Robert B. Benson and Lee H. Patented Aug. 24, 1971 Kaiser A Assignee Allis-Chalmers Manufacturing Company Milwaukee, Wk.

TWO-PIECE PISTON 7 Claims, 6 Drawing Figs.

US. Cl. ..L A counterbalancing device for use an elec.. 92/123, 92/255 trical disconnect switch comprises a cylinder which houses a llll. Cliston a piston rod and a biasing spring which bears against Fleld 0' Search the piston The cylinder is a length of standard metal or 2m, 255, 190 'nbing. The piston rod is a flat bar stock having one or more holes provided along its length. The piston comprises two Rem-mm cued identical separate cast metal semicircular pieces which have UNITED STATES PATENTS reentrant projections on one face thereof which engage a hole 1,462,089 7/ 1923 Lewis 92/ 190 in the piston rod.

{6 0 r/fl Z; I 0 0 1* o E7 (r 24 g Z! Patented Aug. 24, 1971 3,601,014

, T 251T E; wwaww JQ /k PR/ w TWO-PIECE PISTON SUMMARY OF THE INVENTION This invention relates generally to pistons. More particularly it relates to pistons which are used in spring-loaded counterbalancing devices.

Many types of apparatus use counterbalancing devices to make operation thereof easier. For example, disconnect switches employed in the electric utility field have long heavy blades which are pivoted in a vertical plane to open and closed positions. Such switches frequently employ counterbalancing means which take the form of a cylinder in which is located a spring-loaded piston having a piston rod which connects to the switch blade. Heretofore, such counterbalances used a onepiece piston which was bolted or pinned to the end of a piston rod or integral therewith. While such counterbalances were satisfactory for their intended purposes, they did not lend themselves readily to adaptation to different sized switches and they required extra components which needed to be hand assembled during manufacture of the switch.

It is desirable, therefore, to provideimproved counterbalancing devices of the aforesaid character which have a minimum number of parts, which are easily and quickly assembled and which have an inherent versatility which enables them to be employed with apparatus of different sizes and dimensions.

In accordance with the present invention there is provided an improved counterbalancing device of the spring-loaded piston type wherein the piston rod is an elongated member having a plurality of holes therein and wherein the piston comprises two identical separate pieces having projections thereon DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1 of the drawing, the numeral designates a known type of electric disconnect switch which employs a counterblaancing device 12 in accordance with the present invention. Switch 10 comprises a basegportion 14 and an arm or blade 16 which is understood to be rotatable to a limited degree in a vertical plane about a pivot point .18 by suitable operating means (not shown).

AS FIGS. 1 and 2 show, counterbalancing device 12 comprises a cylinder 20 which is affixed to base 14 of the switch by means such as the hole 15, a piston rod 22 which is affixed to blade 16 of switch and to a piston 24 in the cylinder, and biasing means such as springs 26 and 27 which are located in the cylinder and bearing against a portion thereof and cooperate with the piston.

It is to be understood, for example, that when blade 16 of switch 10 is rotated to open position (clockwise with reference to FIG. 1), spring 26, which is a compression spring, tends to expand lengthwise and acts against piston 24 to assist blade opening. Conversely, when blade 16 of switch 10 is rotated to closed position (counterclockwise with reference to 1 FIG. 1) spring 26 tends to resist being compressed as 'piston 24 which are adapted to engage with any one of the holes on the piston rod.

OBJECTS OF THE INVENTION It is an objectof the present invention to provide improved counterbalancing devices.

Another object is to provide improved counterbalancing devices of the spring-loaded piston type wherein having improved pistons and piston rods.

Another object is to provide improved pistons of the aforesaid character which are fabricated in two symmetrical sections and which have improved means whereby they attach to the piston rod.

Another object is to provide improved pistons of the aforesaid character which can be attached at a multiplicity of positions on a piston rod.

Other objects and advantages of the invention will hereinafter appear. I

' DESCRIPTION OF DRAWING The accompanying drawing illustrates a preferred embodiment illustrated is susceptible of modification with respect to details thereof without departing from the scope of the apmoves against it and thereby counterbalances the weight of blade 16.

As FIGS. 2 and 3 shown, piston rod 22 which is in accordance with the present invention takes the form of an elongated member of rectangular cross section having means, such as a plurality of holes 28, 30 and 32 extending transversely therethrough from one side to another of the member, to effect engagement and alignment of components which comprise piston 24. The positioning of the holes is determined by the type and number of applications to which device 12 is desired to be put. More specifically, each hole fixed the location at which piston 24 may be located. In the embodiment shown, for example, piston 24 is located near the end of piston rod 22 but it could be located at holes 30 and 32 of cylinder length or spring length or tension required it. Or, the piston 24 could be reversely disposed as FIG. 6 shows and the spring arrangement changed. Preferably, piston rod 22 is fabricated of commercially available flat bar stock and the holes are punched or drilled therein at desired locations. Piston rod 22 is suitably adaptedat one end 34, as shown in FIG. I, for connection to a member, such as blade 16, which it counterbalances.

Referring to FIGS. 2, 3, 4 and 5 piston 24 comprises a plurality, in this case two, or identical sections or components 36 and 38 whichcombine to form a complete unit. Section 36 for example, comprises a substantially semicircular head portion 40 having two oppositely disposed surfaces 42 and 44, which, for convenience, may be designated front and rear surface, respectively. Means, such as an integrally formed projection 46, extendsoutwardly from the rear surface 44 of section 36 to effect engagement of section ,36 with piston rod 22 and to effect alignment of sections 36 and 38. Projection 46 comprises astraight shank portion 48, an offset intermediate portion 50, and an end tang portion 52. These portions are dimensioned so as to enable offset portion 50 and tang portion 52 to extend through hole 28 in piston rod 22. Shank portion 48 is adapted to be on one side of piston rod 22, offset portion 50 lies in hole 28 and tang portion 52 lies on the other side of piston rod 22 and engages thereagainst. Head portion 40 of section 36 of piston 24 is further provided with a notch or cutout 54 for accommodating piston rod 22. It is to be understood that section 38 of piston 24 is identical to section 36 hereinbefore described. Preferably, the sections 36 and 38 ar fabricated by diecasting.

When both sections 36 and 38 are in place on piston rod 22,. the flat edges 55 of the head portions thereof are in abutment.

Insertion of piston 24 inside of cylinder 20 prevents any movement of either section 36 and 38 by which they would be disengaged from piston rod 22. However, when piston 24 is removed from cylinder 20, the sections may be disengaged from piston rod 22 and relocated thereon if desired.

A piston and piston rod assembly of the aforedescribed character has numerous advantages over conventional assemblies. For example, the piston can be placed at various location on the piston rod and not merely at the end, as FIG. 6 shows. Furthermore, no extraneous member such as nuts, bolts, washers, lockwashers, pins, cutter pins or other fasteners are required to secure the piston and piston rod together. Thus, component and labor cost savings are accomplished in inventory, manufacture and assembly. Also, a given piston and piston rod assembly can be used with switches or other apparatus of different sizes. And, since the two sections of each piston are identical, inventories of these components are simplified. Finally, the nature of the piston rod permits simple adaptations to meet special or new requirements.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In combination:

a piston comprising two identical separate components,

a piston rod,

and means on said components and on said piston rod to effect engagement of each component with said piston rod and alignment of said components,

said means comprising a projection on each of said components and at least one opening in said piston rod engageable with each of said projections.

2. A combination according to claim 1 wherein each projection comprises a shank portion, an offset intermediate portion, and a tang portion.

3. A combination according to claim 2 wherein said means comprises a plurality of openings in said piston 021.

4. A combination according to claim 3 wherein each component comprises a semicircular head having two oppositely disposed surfaces and an edge with said projection extending outwardly from one of said surfaces.

5. A combination according to claim 4 wherein said flat edge is provided with a notch for accommodating said piston rod.

6. A combination according to claim 5 wherein said piston rod has a rectangular cross-sectional configuration and said notch is adapted to receive said piston rod.

7. A combination according to claim 6 including a cylinder in which said piston is disposed and spring means within said cylinder and bearing against a surface of said piston and a portion of said cylinder. 

1. In combination: a piston comprising two identical separate components, a piston rod, and means on said components and on said piston rod to effect engagement of each component with said piston rod and alignment of said components, said means comprising a projection on each of said components and at least one opening in said piston rod engageable with each of said projections.
 2. A combination according to claim 1 wherein each projection comprises a shank portion, an offset intermediate portion, and a tang portion.
 3. A combination according to claim 2 wherein said means comprises a plurality of openings in said piston rod.
 4. A combination according to claim 3 wherein each component comprises a semicircular head having two oppositely disposed surfaces and an edge with said projection extending outwardly from one of said surfaces.
 5. A combination according to claim 4 wherein said flat edge is provided with a notch for accommodating said piston rod.
 6. A combination according to claim 5 wherein said piston rod has a rectangular cross-sectional configuration and said notch is adapted to receive said piston rod.
 7. A combination according to claim 6 including a cylinder in which said piston is disposed and spring means within said cylinder and bearing against a surface of said piston and a portion of said cylinder. 